In a typical radio communications network, wireless terminals, also known as mobile stations and/or user equipments (UE), communicate via a Radio Access Network (RAN) with or via one or more core networks. The radio access network covers a geographical area which is divided into cell areas, with each cell area, or group of cell areas, being served by a base station, e.g., a radio base station (RBS), which in some networks may also be called, for example, a “NodeB” or “eNodeB”. A cell is a geographical area where radio coverage is provided by the radio base station at a base station site or an antenna site in case the antenna and the radio base station are not collocated. Each cell is identified by an identity within the local radio area, which is broadcast in the cell. Another identity identifying the cell uniquely in the whole mobile network is also broadcasted in the cell. The base stations communicate over the air interface operating on radio frequencies with the user equipments within range of the base stations.
In some versions of the RAN, several base stations are typically connected, e.g., by landlines or microwave, to a controller node, such as a radio network controller (RNC) or a base station controller (BSC), which supervises and coordinates various activities of the plural base stations connected thereto. The RNCs are typically connected to one or more core networks.
A Universal Mobile Telecommunications System (UMTS) is a third generation mobile communication system, which evolved from the second generation (2G) Global System for Mobile Communications (GSM). The UMTS terrestrial radio access network (UTRAN) is essentially a RAN using wideband code division multiple access (WCDMA) and/or High Speed Packet Access (HSPA) for user equipments. In a forum known as the Third Generation Partnership Project (3GPP), telecommunications suppliers propose and agree upon standards for third generation networks and UTRAN specifically, and investigate enhanced data rate and radio capacity.
Specifications for the Evolved Packet System (EPS) have been completed within the 3rd Generation Partnership Project (3GPP) and this work continues in the coming 3GPP releases. The EPS comprises the Evolved Universal Terrestrial Radio Access Network (E-UTRAN), also known as the Long Term Evolution (LTE) radio access, and the Evolved Packet Core (EPC), also known as System Architecture Evolution (SAE) core network. E-UTRAN/LTE is a variant of a 3GPP radio access technology wherein the radio base station nodes are directly connected to the EPC core network rather than to RNCs. In general, in E-UTRAN/LTE the functions of a RNC are distributed between the radio base stations nodes, e.g., eNodeBs in LTE, and the core network. As such, the RAN of an EPS system has an essentially “flat” architecture comprising radio base station nodes without reporting to RNCs.
Caching concepts, i.e. caching data intended for a user equipment within the radio communications network, are being considered for radio communications networks for the dual purposes of making more efficient use of network resources and improving the end user service experience, e.g. the Quality of Experience (QoE). Sometimes these two goals can be achieved simultaneously, while other times only one of the aspects may be the target. For instance, by delivering requested content from a network cache instead of a remote server, network resources are saved, while at the same time reducing the download delay experienced by the user.
It is not certain where in the network architecture a cache will be placed. It may be integrated in basically any user plane node or be a stand-alone entity in either the radio access network or the Core Network (CN) or it may be deployed above a Gi interface, which is the IP based interface between the Gateway General Packet Radio Service (GPRS) support node (GGSN) and a Public Data Network (PDN) either directly to the Internet or through a Wireless Application Protocol (WAP) gateway, or an SGi interface, which is the interface between the PDN Gateway (PGW). Currently it seems likely that it will be concluded that downlink data from the cache should pass over the Gi/SGi interface. The main rationale for this probable conclusion is that this makes it straightforward to apply core network functions like charging and lawful interception to the data flows.
In the most common uses of caches data is delivered from the cache on request from a client application or device, such as a UE, but caches may also be used to push data to a client application or device or to deliver data based on delivery subscriptions or delay insensitive requests, e.g. to a UE. A problem with the delivery of cached data arises when the network does not know in which cell the user equipment is located. The user equipment needs to be paged in a lot of cells, which may result in waste of resources such as radio resources and user equipment resources.